We propose to compare the roles played by three motor-related systems in the control of temporally or spatially patterned motor sequences. The three systems are 1) pallidal-thalamo- supplementary motor cortex, 2) cerebello-thalamo-premotor cortex, and 3) cerebello-thalamo-primary motor cortex. Monkeys will be trained to make sequential arm movements under conditions in which 1) sequential spatial or temporal cues are or are not presented, 2) the spatial or temporal motor pattern is actually produced or must only be "internally rehearsed", and 3) the pattern is one that the monkey has practiced and produces using a predictive stategy vs. a random and unpredictable spatial or temporal pattern, in which the monkey responds to the spatial or temporal cue. The contribution of the three systems will be studied during perormance of these motor tasks by 1) recording from neurons in the supplementary motor or lateral premotor cortex, 2) recording from neurons in the thalamus that have been identified physiologically as receiving input from the globus pallidus or different portions of the cerebellar nuclei, and 3) interrupting individual systems, using either chemical inhibition or lesions. These experiments will allow us to test the hypothesis that the basal ganglia and cerebellar output directed to supplementary and lateral premotor areas of cortex contribute differentially to the control of sensory-guided vs. "internally programmed" or "learned" complex motor sequences.